From: Alan Stern stern@rowland.harvard.edu
commit ed9de4ed39875706607fb08118a58344ae6c5f42 upstream.
The syzbot fuzzer detected a problem in the udlfb driver, caused by an endpoint not having the expected type:
usb 1-1: Read EDID byte 0 failed: -71 usb 1-1: Unable to get valid EDID from device/display ------------[ cut here ]------------ usb 1-1: BOGUS urb xfer, pipe 3 != type 1 WARNING: CPU: 0 PID: 9 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504 Modules linked in: CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.4.0-rc1-syzkaller-00016-ga4422ff22142 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 Workqueue: usb_hub_wq hub_event RIP: 0010:usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504 ... Call Trace: <TASK> dlfb_submit_urb+0x92/0x180 drivers/video/fbdev/udlfb.c:1980 dlfb_set_video_mode+0x21f0/0x2950 drivers/video/fbdev/udlfb.c:315 dlfb_ops_set_par+0x2a7/0x8d0 drivers/video/fbdev/udlfb.c:1111 dlfb_usb_probe+0x149a/0x2710 drivers/video/fbdev/udlfb.c:1743
The current approach for this issue failed to catch the problem because it only checks for the existence of a bulk-OUT endpoint; it doesn't check whether this endpoint is the one that the driver will actually use.
We can fix the problem by instead checking that the endpoint used by the driver does exist and is bulk-OUT.
Reported-and-tested-by: syzbot+0e22d63dcebb802b9bc8@syzkaller.appspotmail.com Signed-off-by: Alan Stern stern@rowland.harvard.edu CC: Pavel Skripkin paskripkin@gmail.com Fixes: aaf7dbe07385 ("video: fbdev: udlfb: properly check endpoint type") Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/video/fbdev/udlfb.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
--- a/drivers/video/fbdev/udlfb.c +++ b/drivers/video/fbdev/udlfb.c @@ -27,6 +27,8 @@ #include <video/udlfb.h> #include "edid.h"
+#define OUT_EP_NUM 1 /* The endpoint number we will use */ + static const struct fb_fix_screeninfo dlfb_fix = { .id = "udlfb", .type = FB_TYPE_PACKED_PIXELS, @@ -1652,7 +1654,7 @@ static int dlfb_usb_probe(struct usb_int struct fb_info *info; int retval; struct usb_device *usbdev = interface_to_usbdev(intf); - struct usb_endpoint_descriptor *out; + static u8 out_ep[] = {OUT_EP_NUM + USB_DIR_OUT, 0};
/* usb initialization */ dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL); @@ -1666,9 +1668,9 @@ static int dlfb_usb_probe(struct usb_int dlfb->udev = usb_get_dev(usbdev); usb_set_intfdata(intf, dlfb);
- retval = usb_find_common_endpoints(intf->cur_altsetting, NULL, &out, NULL, NULL); - if (retval) { - dev_err(&intf->dev, "Device should have at lease 1 bulk endpoint!\n"); + if (!usb_check_bulk_endpoints(intf, out_ep)) { + dev_err(&intf->dev, "Invalid DisplayLink device!\n"); + retval = -EINVAL; goto error; }
@@ -1927,7 +1929,8 @@ retry: }
/* urb->transfer_buffer_length set to actual before submit */ - usb_fill_bulk_urb(urb, dlfb->udev, usb_sndbulkpipe(dlfb->udev, 1), + usb_fill_bulk_urb(urb, dlfb->udev, + usb_sndbulkpipe(dlfb->udev, OUT_EP_NUM), buf, size, dlfb_urb_completion, unode); urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;